7/30/2019 Polonium 210

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P H Y S I C A L S C I E N C E S M A G A Z I N E

Polonium 210

The death of the Russian ex-spy Alexander Litvinenko has been linked to the presence of a"major dose" of radioactive polonium-210 in his body. Traces of the radioactive substancehave since been discovered at various locations in London visited by Mr Litvinenko as well asin Russia and on two British Airways (BA) flights

What is polonium-210?It is a naturally occurring radioactive material that emits highly hazardous alpha (positivelycharged) particles. It was first discovered by Marie Curie at the end of the 19th century. One ton of uranium ore contains only

about 100 micrograms (0.0001 grams) of polonium.

There are very small amounts of polonium-210 in the soil and in the atmosphere, and everyone has a small amount of it in theirbody. But at high doses, it damages tissues and organs. Philip Walker, professor of physics, University of Surrey said: "This seemsto have been a substance carefully chosen for its ability to be hard to detect in a person who has ingested it."

What is the risk to other people from the dose Mr Litvinenko received?It cannot pass through the skin, and must be ingested or inhaled into the body to cause damage. The radiation has a very shortrange, so it only harms nearby tissue.

Where does polonium-210 usually occur?It has industrial uses such as static control and as a heat source for satellite power supplies, but is not available in these areasin a form conducive to easy poisoning.

Due to its scarcity, polonium is usually produced by bombarding bismuth-209 with neutrons in a nuclear reactor. This formsbismuth-210, which has a half-life of 5 days. Bismuth-210 decays into polonium-210 through beta decay. Milligram amountsof polonium-210 have been produced by this method. A single gram of polonium-210 creates 140 Watts of heat energy and is

being considered as a lightweight heat source for thermoelectric power for spacecraft. Polonium-210 has a half-life of 138.39days.It is also present in tobacco.

Professor Dudley Goodhead, Medical Research Council Radiation and Genome Stability Unit, said: "To poison someone much largeramounts are required and this would have to be man-made, perhaps from particle accelerator or a nuclear reactor."

Where would someone obtain polonium-210 from?Although it occurs naturally in the environment, acquiring enough of it to kill would require individuals with expertise and

connections. It would also need sophisticated lab facilities - and access to a nuclear reactor. Alternatively, it could have beenobtained from a commercial supplier.